This invention relates to mechanical face seals which provide a fluid-tight seal between a housing and a rotatable shaft. More particularly, it relates to such seals that include a finger-type spring to provide an axial bias and a secondary seal formed of a rubber or elastomeric bellows.
Seals of the general type are large volume, low cost and are particularly suitable for use in automotive water pumps. Other applications of such seals include other water pumps, such as marine bilge pumps, and pumps for various other liquids.
Seals currently in common use typically include a primary and mating ring defining relatively rotating sealing faces. These rings may be made of silicon carbide or carbon. A coil spring provides an axial bias, and an elastomeric or rubber bellows provides a secondary seal between the axially movable primary ring and its associated housing or shaft. Examples are found in U.S. Pat. Nos. 4,275,889; 4,779,876 and 5,199,719. Similar seals that have a different form of secondary seal or biasing means are shown in U.S. Pat. Nos. 4,754,981 and 5,947,479.
Bellows-type seals have enjoyed significant commercial success. Ongoing demand for improved productivity, reliability, durability and changing envelope requirements within the associated pump dictate continued effort for new developments. The present invention represents an advance in seal technology that addresses these needs.
The present invention is directed to a mechanical seal assembly which utilizes a finger-type spring to provide the axial load upon the axially movable seal ring. Also, a unique elastomeric bellows is provided which provides the secondary seal and includes a single convolution between its connection to the axially movable seal ring and its connection to the associated housing or shaft.
The invention comprises, in the broadest form, a mechanical end face seal assembly to provide a fluid tight seal between a housing defining a bore and a rotatable shaft extending through the bore, the seal assembly comprising an annular mating seal ring, an axially movable annular primary seal ring, the rings each having a seal face in facing relation to the seal face of the other ring to define a sealing interface therebetween, a resilient bellows in fluid-tight sealing relation to the primary ring and adapted to be in fluid-tight sealing relation to a housing or shaft, the bellows including an inboard web and an outboard web, a base connecting said webs to form a single convolution, a finger spring member adapted to urge the primary ring toward the mating seal ring, the finger spring member including a plurality of spring fingers adapted to be deformed on installation of said seal assembly between the housing and shaft, the finger spring being nested within the single convolution.